1. Kingdom Protista
Chapter 18

2. Outline Introduction Features of Kingdom Protista Algae
Phylum Chlorophyta – The Green Algae
Phylum Chromophyta – The Yellow-Green Algae, Golden- Brown Algae, Diatoms, and Brown Algae
Phylum Rhodophyta – The Red Algae
Phylum Euglenophyta – The Euglenoids
Phylum Dinophyta – The Dinoflagellates
Phylum Cryptophyta – The Cryptomonads
Phylum Prymnesiophyta (Haptophyta) – The Haptophytes
Phylum Charophyta – The Stoneworts
Human and Ecological Relevance of the Algae

3. Outline cont’d. Phylum Myxomycota – The Plasmodial Slime Molds
Phylum Dictyosteliomycota – The Cellular Slime Molds
Phylum Oomycota – The Water Molds

4. Introduction < 1 bya, organisms confined to oceans
Protected from drying out, UV radiation, and large fluctuations in temperature
Absorbed nutrients directly from H2O
Ca. 400 mya, green algae began making transition from H2O to land
Gave rise to green plants
Coleochaete probably indirect ancestor of land plants
Shares features with land plants: parenchyma-like cells, cell plate and phragmoplast during mitosis, protective covering for zygote, and production of lignin-like compound
Coleochaete

5. Features of Kingdom Protista
Domain Eukarya - all members have eukaryotic cells
Includes Kingdoms Protista, Plantae, Fungi, Animalia
Organisms in Protista diverse and heterogeneous
Nutrition varied: photosynthetic, ingestion of food, absorption of food
Individual life cycles vary considerably
Reproduction generally by cell division and sexual processes
Algae in Kingdom Protista
Grouped into several phyla based on form of reproductive cells, and combinations of pigments and food reserves

6. Phylum Chlorophyta Green Algae
Unicellular, filamentous, platelike colonies, netlike tubes, hollow spheres, lettuce-like leaves
Greatest variety in freshwater lakes, ponds, and streams
Have chlorophylls a and b
Store food as starch
Most have single nucleus per cell
Most reproduce both sexually and asexually

7. Phylum Chlorophyta Chlamydomonas Common in freshwater pools
Unicellular
Pair of whip-like flagella
2 or more vacuoles at base of flagella
Regulate H2O content of cell and remove waste
Single, cup-shaped chloroplast with 1 or 2 pyrenoids inside
Pyrenoids - proteinaceous structures associated with synthesis of starch
Red eyespot near base of flagella
Allows alga to swim toward light

8. Phylum Chlorophyta
Chlamydomonas

9. Phylum Chlorophyta Chlamydomonas asexual reproduction:
Nucleus divides by mitosis, and cell contents become 2 daughter cells within cellulose wall
Each develop flagella and swim away
No change in chromosome number; all cells 1n

10. Phylum Chlorophyta
Chlamydomonas sexual reproduction:

11. Phylum Chlorophyta Ulothrix Filamentous with holdfast cell at one end
Single, wide, curved, somewhat flattened chloroplast, with 1-several pyrenoids

12. Phylum Chlorophyta Spirogyra (watersilk)
Filaments of cylindrical cells
Frequently floats in masses on surface of quiet freshwater
Chloroplast ribbon-shaped and spirally wrapped around vacuole, with pyrenoids at regular intervals
Asexual reproduction by fragmentation of filament

13. Phylum Chlorophyta Spirogyra (watersilk) cont’d.
Sexual reproduction by conjugation

14. Phylum Chlorophyta Oedogonium
Epiphytic filamentous green alga with holdfast
Large netlike chloroplast with pyrenoids at intersections of net
Asexual reproduction by fragmentation or by zoospores
Zoospores produced singly in cells at tips of filaments and have ca. 120 flagella forming fringe at one end
Sexual reproduction by oogamy - 1 gamete motile and other stationary and large

15. Phylum Chlorophyta
Oedogonium sexual reproduction

16. Phylum Chlorophyta Other green algae
Chlorella - widespread green alga composed of tiny spherical cells
Only reproduce asexually by forming either daughter cells or autospores through mitosis
Used in research; may become important as food source
Desmids - mostly free-floating and unicellular
Reproduce by conjugation
Closterium, a desmid

17. Phylum Chlorophyta Other green algae cont’d.
Hydrodictyon (water nets) - net-like, tubular colonies with hexagonal or polygonal meshes
Asexual reproduction and isogamous sexual reproduction
Isogamous - 2 flagellated gametes

18. Phylum Chlorophyta Other green algae cont’d.
Acetabularia (mermaid’s wineglass) - consists of single, huge cell shaped like delicate mushroom
Used in classic experiments demonstrating influence of nucleus on form of cell
Isogamous sexual reproduction

19. Phylum Chlorophyta Other green algae cont’d.
Volvox - colonial green algae held together in secretion of gelatinous material, resembling hollow ball
Reproduction asexual or sexual
Smaller daughter colonies formed inside parent colony

20. Phylum Chlorophyta Other green algae cont’d.
Ulva (sea lettuce) - multicellular seaweed with flattened green blades and basal holdfast to anchor blades to rocks
1n and 2n blades
2n blades produce spores developing into 1n blades
1n blades bear gametangia - form gametes
Zygotes grow into 2n blades
1n and 2n blades indistinguishable = isomorphic

21. Phylum Chromophyta Yellow-green algae (Xanthophyceae)
Mostly freshwater, with few marine and terrestrial species
2 flagella of motile cells oriented in opposite directions
Vaucheria - Oogamous, coenocytic, filamentous species
Aplanospores formed during asexual reproduction
Sexual reproduction rare
Stipitococcus, a yellow-green algae
Sexual reproduction in Vaucheria

22. Phylum Chromophyta Golden-brown algae (Chrysophyceae)
Most occur in plankton of fresh H2O
Motile cells have 2 flagella of unequal length inserted at right angles to each other
Photoreceptor on short flagellum

23. Phylum Chromophyta Diatoms (Bacillariophyceae) Unicellular
Fresh and salt H2O, particularly abundant in cold marine habitats
Dominate algal flora on damp cliffs, tree bark or buildings
Look like ornate, glass boxes with lids
95% of wall silica
Chlorophylls a and c and fucoxanthin
Food reserves = oil, fats or laminarin

24. Phylum Chromophyta
Diatoms (Bacillariophyceae) cont’d.

25. Phylum Chromophyta Brown algae (Phaeophyceae)
Relatively large; none unicellular or colonial
Most marine; majority in cold, shallow H2O
Many have thallus differentiated into holdfast, stipe, and blades
Blades may have gas-filled bladders
Chlorophylls a and c, fucoxanthin
Food reserve = laminarin
Algin in cell walls
Nereocystis, a kelp

26. Phylum Chromophyta Brown algae (Phaeophyceae) cont’d.
Sargassum - floating brown seaweed
Asexual reproduction by fragmentation or autospores
Sargassum

27. Phylum Chromophyta Brown algae (Phaeophyceae) Fucus (Common rockweed)
Sexual reproduction

28. Phylum Rhodophyta Red algae
In warmer and deeper waters than brown algae
Most filamentous with filaments so tightly packed they appear to have flattened blades or branched segments

29. Phylum Rhodophyta Red algae cont’d.
Relatively complex life cycle involving 3 types of thallus structures
Nonmotile reproductive cells

30. Phylum Rhodophyta Red algae cont’d. Colors mostly due to phycobilins
Similar to those of cyanobacteria
Red algae may have been derived from cyanobacteria
Chlorophylls a, c, and sometimes d
Food reserve - Floridean starch
Numbers of species produce agar

31. Phylum Euglenophyta Euglenoids
No cell wall; pellicle = plasma membrane and underlying strips that spiral around cell
Flagellum
Gullet ingests food
Ca. 1/3 of species have disc-shaped chloroplasts
Red eyespot for light detection
Paramylon food reserve
Asexual reproduction by cell division.
Sexual reproduction not confirmed

32. Phylum Dinophyta Dinoflagellates
Red tides - sudden multiplication of dinoflagellates
Some produce neurotoxins that accumulate in shell fish
Cellulose “armor plates” inside cell membrane
2 flagella in intersecting grooves
One acts as rudder
Other gives cell spinning motion

33. Phylum Dinophyta Dinoflagellates cont’d.
Most have disc-shaped chloroplasts
Contain xanthophyll pigments
Chlorophylls a and c
Ca. 45% non-photosynthetic
Chromosomes remain condensed and visible throughout life of cell
Food reserve = starch
Many have tiny projectiles that fire when irritated

34. Phylum Cryptophyta Cryptomonads Marine and freshwater 2 flagella
Plates on inside of plasma membrane
Single, 2-lobed chloroplast with starch granules surrounding central pyrenoid
Nucleomorph - estigial nucleus of primitive symbiotic organism
Gullet with ejectosomes - aid in propulsion
Sexual reproduction unknown

35. Phylum Prymnesiophyta (Haptophyta)
Haptophytes
Fresh and saltwater; major component of marine plankton
Most unicellular, with 2 smooth flagella of similar length inserted at apex
Pigments and food reserve similar to Chromophyta
Haptonema – 3rd flagellum located between 2 flagella
Aids in food capture
Often covered in scales
2 disc-shaped chloroplasts

36. Phylum Charophyta Stoneworts Shallow, freshwater lakes and ponds
Often precipitate Ca salts on surfaces
Axis with short lateral branches in whorls
Sexual reproduction is oogamous
Multicellular antheridia

37. Human and Ecological Relevance of Algae
Protistan algal phyla at bottom of food chain
Diatoms
Oils sources of vitamins
Diatomaceous earth
Filtration
Polishes, toothpaste
Paint that reflects light
Other algae
Chlorella
Potential human food source

38. Human and Ecological Relevance of Algae
Algin
Produced by giant kelps and other brown algae
Ice cream, salad dressing
Latex paint, textiles, ceramics
Regulates H2O behavior
Controls development of ice crystals
Regulates penetration of water
Stabilizes suspensions
Vessel harvesting kelp

39. Human and Ecological Relevance of Algae
Minerals and food
Iodine from kelp
Red algae
Food - Dulse, nori
Carrageenan - thickening agent
Agar
Produced by red alga Gelidium
Solidifier of nutrient culture media
Retains moistness in bakery products
Base for cosmetics

40. Phylum Myxomycota Plasmodial slime molds Without chlorophyll
Feed on bacteria and other organic particles
Consist of plasmodium
Protoplasm containing many 2n nuclei
No cell wall
Flows rapidly and rhythmically
Found on damp forest debris, under logs, on dead organic material
Plasmodium

41. Sporangia from various plasmodial slime molds
Phylum Myxomycota
Plasmodial slime molds cont’d.
Sexual reproduction:
Plasmodium converts into separate small sporangia containing spores
Sporangia from various plasmodial slime molds

42. Phylum Myxomycota Plasmodial slime molds cont’d.
Sexual reproduction of plasmodial slime mold:

43. Phylum Dictyosteliomycota
Cellular slime molds
Individual amoebalike cells feed independently, dividing and producing separate new cells periodically
Clump together to form mass called pseudoplasmodium
Crawls like a garden slug
Eventually transforms into sporangium-like mass of spores
Human and ecological relevance of the slime molds
Break down organic particles to simpler substances

44. Phylum Oomycota Water molds
Cottony growths on fish; often found on dead insects
Range in form from single spherical cells to branching, threadlike, coenocytic hyphae
Coenocytic hyphae not divided into individual cells and may form large thread masses (mycelia)
Share features with brown algae, including oogamy, cellulose in cell walls, predominantly 2n lifecycle, and zoospores with 2 flagella
Asexual reproduction:
Crosswalls form at tips of hyphae
Zoospores produced inside and emerge through pore

45. Phylum Oomycota Water molds cont’d. Sexual reproduction:
Meiosis takes place in oogonia and antheridia
Zygotes formed in oogonia give rise to new mycelia
Human and ecological significance of water molds:
Downy mildew on grapes
Potato blight

46. Review Introduction Features of Kingdom Protista Algae
Phylum Chlorophyta – The Green Algae
Phylum Chromophyta – The Yellow-Green Algae, Golden- Brown Algae, Diatoms, and Brown Algae
Phylum Rhodophyta – The Red Algae
Phylum Euglenophyta – The Euglenoids
Phylum Dinophyta – The Dinoflagellates
Phylum Cryptophyta – The Cryptomonads
Phylum Prymnesiophyta (Haptophyta) – The Haptophytes
Phylum Charophyta – The Stoneworts
Human and Ecological Relevance of the Algae

47. Review cont’d. Phylum Myxomycota – The Plasmodial Slime Molds
Phylum Dictyosteliomycota – The Cellular Slime Molds
Phylum Oomycota – The Water Molds